Heron, common name for members of a family of tall wading birds of the stork order, found in wet areas (a few species in upland grassy areas) in all temperate and tropical parts of the world. Included among the herons are several groups of birds more commonly known as bitterns, boatbills, and egrets.

Herons have elongated necks, legs, and bills. Cranes, which somewhat resemble the larger herons, fly with their necks extended; herons fly with their necks bent in an S shape, with their heads supported between their shoulders. Their bills are sharp edged and pointed. Herons have four long-clawed toes on each foot, three of which are directed forwards, and the fourth, backwards. The claw on the middle of the forward toes has a rough, comb-like inner margin that is used by the heron to preen its soft plumage. During the breeding season, many herons have elongated plumes, variously on the head, back, or breast. The birds mate and nest in large groups known as heronries. Most species construct their loose, flat, platform-style nests high in the branches of swamp trees. Notable exceptions are the bitterns, which are solitary rather than colonial and build their nests among reeds on the ground. Two to six pale blue eggs are laid in a clutch. Most herons feed on aquatic animal life, but some eat insects and even mice. Most species do not stalk their prey but, waiting in shallow water or on land, spear it with their long bills.

One of the largest species is the great blue heron, which is widely distributed in North America and winters as far south as northern South America. This bird is about 117 cm (46 in) long and has a wingspan of about 1.8 m (6 ft). Above, it is bluish-grey; the belly is black. Its head is white, with a black stripe along the sides of the crown; in the breeding season this stripe extends to elongated black plumes. The neck is grey, with a central line of black spots down the front edge. An all-white, egret-like colour phase called the great white heron occurs in Florida and the Caribbean. The grey heron is widely distributed in Eurasia. It closely resembles the great blue heron but is smaller (about 90 cm/36 in) and paler in colour. Its chief food is fish, which it catches in fresh water and estuaries. The purple heron of the northern Mediterranean countries has golden brown plumage on its back and the back of the neck. The buff coloured squacco heron is the smallest (45 cm/18 in), revealing its white wings in flight. It breeds on the Mediterranean coast and winters in Africa, south of the Sahara. Even more widely distributed is the green-backed heron, which has many subspecies in Eurasia as well as in the Americas. It has a shiny dark green back mixed with bluish-grey; deep chestnut face and neck; white belly; and greenish-black crown feathers, which can be erected into a shaggy crest.

The night herons form a nearly worldwide group of seven species of large-eyed nocturnal herons. The black-crowned night heron occurs in the Mediterranean region and North America.

Scientific classification: Herons belong to the family Ardeidae of the order Ciconiiformes. The great blue heron is classified as Ardea herodias, the grey heron as Ardea cinerea, the purple heron as Ardea purpurea, the squacco heron as Ardeola ralloides, and the green-backed heron as Butorides striatus. The black-crowned night heron is classified as Nycticorax nycticorax.